Some amino alcohols may be represented by the general formula:
These amino alcohols can be valuable materials because they may be used as solvents, intermediates for making surface active agents, corrosion inhibitors in metal working fluids, neutralizing agents in acid scrubbing during natural gas or syngas purification processes, and aids in the preparation of compounds for use in the pharmaceutical industry.
Currently, processes exist for the preparation of amino alcohols. Such processes can involve reacting polyhydroxy compounds, such as ethylene glycol, 1,2-diols, 1,3-diols, and polyglycols, with amine compounds and hydrogen in the presence of a heterogeneous catalyst. One concern with such processes is that they can exhibit poor-to-moderate conversions and selectivities. This undesired outcome can result from the fact that the reactions can yield complex product mixtures consisting of amino alcohols, di-and tri-amines, oligomeric polyamines, cyclic amines (e.g. pyrrolidines, piperidines, and piperazines), unreacted starting materials and other unidentified compounds. Examples of these catalysts and processes can be found in U.S. Pat. Nos. 6,376,713; 6,057,442; 5,288,911; 4,123,462; 4,151,204; and 4,111,840.
Alternately, amino alcohols can be prepared by reacting an amine compound with 2-chloro-1-propanol (see, for example, JP 01056652) or by stoichiometric reduction of the corresponding amino acids and ester derivatives with a variety of reducing reagents (A. Abiko et al., Tetrahedron Lett. 1992, 33, 5517; M. J. McKennon, et al., J. Org. Chem. 1993, 58, 3568, and references therein) and by catalytic hydrogenation of amino acids, for example as reported in U.S. Pat. Nos. 5,536,879; 5,731,479; and 6,310,254. In works described by Miller, et al., (Organic Letters, 2003, 5(4), 527) on the conversion of alanine to desired products it is stressed the importance of performing hydrogenations at low pH such that the amino acid is in the protonated form rather than carboxylate form. In general, the catalytic hydrogenation of amino acids require a low solution pH in conjunction with high catalyst loading, prolonged reaction times, and high hydrogen pressure. Thus, these processes can often be costly since additional expensive feedstocks and reagents are needed.
Therefore, there remains a need for processes for making amino alcohols from inexpensive feedstocks, such as crude glycerol, which can also reduce or eliminate the production of substantial amounts of undesired byproducts.